Device for preparing transformers

ABSTRACT

The invention relates to a device for heating and drying parts ( 2 ) with cellulose or plastic based hygroscopic electroinsulations, especially for the preparation of new or used transformers, condensers, instrument transformers or electric leadthroughs in a vacuum by means of condensation heat from the steam of a heating fluid (a solvent, kerosine). During heating, at least one higher-boiling second liquid, such as transformer oil, results from said parts ( 2 ). The inventive device also comprises a vessel, a vacuum pump ( 10 ), at least one condenser ( 3  and/or  8 ) and a heat exchanger ( 16 ) for the heating fluid. In order to provide a mobile system enabling local treatment of transistors ( 2 ) which are already in operation, the heat exchanger ( 16 ) heats the heating fluid in the liquid phase and evaporation occurs on or in the vessel, for example, via expansion valves ( 18 ) and/or in an expansion container or evaporator arranged directly on the vessel.

SPECIFICATION

[0001] The invention relates to a device for heating and drying parts asgenerically defined by the preamble to claim 1.

[0002] To avoid failures, power transformers in substations in theelectrical energy supply grid require preventive preparations of theirhygroscopic insulations. This is also true after repairs or ifmalfunctions have occurred, if after the apparatuses have been openedthe hygroscopic insulations of the transformers have absorbed moistureand gas from the ambient air, reducing their insulating properties.Deposits of aging products also adversely affect the insulatingcapability.

[0003] In maintenance or in the event of minor malfunctions, the activepart of the transformer can stay in the housing and be re-preparedlocally, that is, in the substation, for further use. Several methodsalready exist for accomplishing this.

[0004] Preparation by means of the insulating oil is a widely usedmethod. In it, the operating oil is drawn from the transformer by arecirculating process, carried in a closed loop through a vacuumpreparation system, demoistened and degassed in the process, andreturned to the transformer. By the contact of the dried oil with theinsulation, a withdrawal of moisture from the insulation thus takesplace indirectly via the preparation system.

[0005] In a further process, known as the “oil spray process”, oil isfor the most part drained out of the transformer, so that theinsulations can be exposed to the vacuum. By spraying insulating oilinto the interior of the transformer, the transformer is heated, and theevaporating moisture is aspirated by a vacuum pump connected to it.

[0006] Combinations of the aforementioned processes also exist inconjunction with recirculated hot air or partial direct heating of thewindings by passing an electrical current through them.

[0007] All the above methods, however, have the disadvantage that thetemperature range for the drying is very severely limited by thepresence and use of the insulating oil. The impregnation also severelyimpairs the diffusion of water vapor. The preparation process istherefore extremely time-consuming. A further disadvantage is that theinsulation is inadequately heated at places that are unfavorable interms of flow and especially in poorly accessible conduits is notcleaned of the deposits.

[0008] In the event of major defects, the transformer must therefore betransported away from the distributor station to a repair facility,where it is broken down, repaired, and then re-prepared as describedabove.

[0009] Nowadays the insulations of power transformers, and especiallythe windings assembled to make the active part, are typically dried,upon initial production, at the producing factory by so-calledvapor-phase processes in accordance with German Patent Disclosures DE198 26 682 A1, DE 196 37 313 A1, or German Patent DE 44 46 204 C1. Inthese processes, the active part with the insulator parts contained init is heated in a large vacuum autoclave with the solvent vapor,produced in an evaporator, and in the process subjected to intensivecleaning.

[0010] These methods are extremely effective, but they are poorly suitedto on-site preparation of transformers that are already in operation,since the large cross sections toward the transformer that are requiredfor delivering the heat transfer medium in vapor form cannot be achievedin a portable drying device.

[0011] With this as the point of departure, it is the object of theinvention to overcome the aforementioned disadvantages and to preparetransformers, especially on-site, and in the process subject them to anintensive washing process. In this process, the absorbed oil shouldpreferably also be precipitated out.

[0012] According to the invention, this object is attained by a devicehaving the characteristics of claim 1. Embodiments of the invention arethe subjects of dependent claims.

[0013] Since with the invention as many of the advantages named in thethree references cited above are to be attained or preserved, theteaching in these references is hereby explicitly fully incorporated byreference.

[0014] According to the invention, a heat exchanger heats the heatingfluid in such a way that it stays in the liquid phase. The evaporationdoes not take place until on or in the vessel, for example via expansionvalves, or in an expansion container disposed directly on the vessel,via the pressure drop that takes place there, or via a separateevaporator.

[0015] The device can be either stationary or mobile, in which case theboiler of the transformer to be heated can be used as the vessel. It isfavorable if the connections between the heat exchanger that heats theheating fluid and the expansion valves and/or between an outlet valvefrom the boiler and a feed pump of the system and/or between the boilerand one or more blocking valves are disconnectable. Then the system caneasily be transported to its applicable locations of use and connectedthere.

[0016] If a removable exchange container is used for the heating fluid,then used heating fluid, whose properties have been impaired bytransformer oil, can be removed directly and prepared elsewhere, and newfluid can very easily be supplied to the transformer.

[0017] To improve the efficiency, the transformer boiler can be heatedin insulated fashion or externally by portable insulating means, such asinsulating plates, insulating mats, wall elements, single- ordouble-walled supporting air tents, or by portable supplementaryheaters; for mobile operation, air heaters are an attractive choice.

[0018] Instead of expansion valves, which expand the heating fluid intothe boiler and cause it to evaporate there, an expansion container witha short line to the boiler can also be used to evaporate the heatingfluid. This expansion container can have a return line for theunevaporated heating fluid. The critical path for the evaporated heatingfluid thus once again remains short, as desired.

[0019] The expansion container can also be disposed on the transformerboiler. Once again, a short line to the transformer boiler for theevaporated heating fluid is important. If an inlet line to a condenseris provided, then once the heating is concluded, better distillation ofthe solvent portion off from the mixture is possible.

[0020] If the expansion container has a permeable double jacket, thenthe heated heating fluid, to cover the heat losses, can flow through theexpansion container before being evaporated.

[0021] In one version of the invention, it is additionally possible, forseparating the already-concentrated heating fluid flowing out of theexpansion container, to provide a thin-film evaporator. If the thin-filmevaporator has an inlet line to a condenser, then the vapor that occursat reduced pressure can be delivered directly to the condenser.

[0022] In a further version, a lightweight, compact thin-filmevaporator, such as a plate evaporator, can be secured directly to thetransformer boiler. Once again, short paths for the vapor are thenattained.

[0023] In a further embodiment of the invention, it is provided that thealready-concentrated proportion flowing out of the expansion containeris delivered through a valve and a pressure barrier by gravity to adownstream thin-film evaporator for filtering off the rest of thesolvent, and the vapor occurring when the pressure has been lowered isdelivered through the valve directly to the condenser. In still anotherembodiment of the invention, it is provided that the pressure barrier isformed by a feed pump with a valve circuit, and the post-evaporator isset up inside the mobile system. It is attained as a result that in thepreparatory phase the evaporator need not be secured to the transformerboiler, which considerably reduces the manual effort required.

[0024] If the transformer is located so low that there is no space tohold the heating fluid flowing out of the vessel, then a feed pump,designed for low inlet heights, which is preferably embodied as a liquidring pump or as a positive displacement pump, and an intermediatecontainer, disposed at a higher level are used, with a downstreamcentrifugal ring pump for the further pumping of the heating fluid intothe heat exchanger and/or into the evaporators. The intermediatecontainer thus makes an adequate inlet height for the centrifugal pumppossible.

[0025] For more-effective cleaning of the solvent at the end of theheating and after the conclusion of the pressure reduction, a thin-filmevaporator, with an inlet line to a condenser and with an outlet line tothe exchange container, can be provided.

[0026] Further objects, advantages, characteristics and possible uses ofthe present invention will become apparent from the ensuing descriptionof the exemplary embodiments in conjunction with the drawings. All thecharacteristics described and/or shown in the drawings, on their own orin arbitrary useful combination, form the subject of the presentinvention, independently of how they are combined in the claims or ofthe claims dependency.

[0027] Shown are:

[0028]FIG. 1, an embodiment of a device according to the invention withdirect evaporation in the transformer boiler;

[0029]FIGS. 2 and 3, embodiments according to the invention withexpansion containers;

[0030]FIG. 4, an exemplary embodiment similar to FIGS. 2 and 3, but withan additional thin-film evaporator;

[0031]FIG. 5, an embodiment according to the invention with anintermediate container for the fluid; and

[0032]FIGS. 6 and 7, two further versions with thin-film evaporators.

[0033] The device of FIG. 1 has a transformer boiler 1, in which thepart or parts 2 to be treated, such as an active part 2, are located.The drying system of FIG. 1 is advantageously connected to thetransformer boiler 1 by flexible connecting lines. Two condensers 3 and8 are connected via the valves 4, 6 and 7. The condenser 8 is cooled bythe cooling system 9. A vacuum pump 10 is connected to it. Theseparation container 5 is connected to the condenser 3. From the sump ofthe condenser 3, a line including a feed pump 19 leads to an outletvalve 20. From its middle region, a line leads via a valve 11 to thelevel sensor 13 and to a feed pump 14. The line also leads via valves 21and 23 to an exchange container 24. From the sump 1.1 of the boil 1, aline with a valve 12 also leads to the feed pump 14. A tie line with avalve 22 branches off between the valves 21 and 23 and leads to theoutlet of the feed pump 14. From there, a line leads via the filter 15to the heat exchanger 16 for the heating fluid. The heat exchanger 16 isheated by the heater 17. A line carries heated heating fluid to theexpansion valves 18 provided on the boiler 1.

[0034] In a mobile system, flexible, removable connections between thetransformer boiler 1 and the system are provided, for instance betweenthe components 16 and 18, 12 and 14, and between 1 and 7 and 1 and 4.

[0035] The function of such a system, and the possible procedures therefor heating, reducing pressure, and regenerating the fluid, have alreadybeen described at length with respect to stationary systems in theGerman references cited, DE 198 26 682 A1, DE 196 37 313 A1, and DE 4446 204 C1.

[0036] As the heat transfer medium, as in the non-mobile vapor phasesystems, a heating fluid which is a solvent, such as kerosene, is used.According to the invention, the solvent is heated in liquid form in theheat exchanger 16 and injected into the transformer interior 1 via theexpansion valves 18. Upon entry into the interior 1 of the transformer,which has been evacuated by the vacuum pump 10, some of the liquidsolvent evaporates and transfers the condensation heat, from the ensuingcondensation on the colder parts of the active part 2 of thetransformer, to these colder places and thus heats them up.

[0037] The unevaporated portion of the solvent, acting as a heatreservoir, flows together with the condensate via the insulation of theactive part 2 and thus contributes to the heating and simultaneouslytakes part in the cleaning process. Contaminants are carried out via thefeed pump 14 and are filtered out of the loop in the filter 15.

[0038] Since the solvent is a good solvent, the oil adhering to and inthe insulation is washed out to a maximum extent and dissolved in thesolvent. The mixture is delivered to the feed pump 14 via the valve 12.By de-oiling the insulation and because of the absence of oxygen, theusual elevated temperatures for vapor phase processes can be employed.Because of the reduced proportion of oil, on the one hand a higheroperating temperature is possible, and on the other, higher diffusion ofwater vapor is achieved.

[0039] By means of a suitable control device, the pump 14 is initiallysupplied with solvent from the reserve container 24 via the valves 21,23 and 11. The condensate flowing out from the transformer and theunevaporated portion form an increasing buffer volume 1.1 on the bottomof the transformer. Once the buffer volume 1.1 is sufficient, the valve12 is opened and the valve 21 is closed, creating a closed loop. In thisway, the active part 2, located in its own housing 1, is heated to therequisite drying temperature. In the process, the radiator valves areclosed. The transformer housing 1 can be protected from outside by asuitable heat insulation, to reduce heat losses.

[0040] The solvent quantity that must be made available in the completedrying and cleaning process is determined in accordance with theexpected quantity of oil. For especially large transformers, provisionis made for exchanging the container 24 with the used solvent (heattransfer medium) for a container with cleaned solvent during theprocess. To filter off the dissolved oil, the container with thecontaminated solvent is either brought to a large vapor phase apparatusor connected to a solvent recovery system. In this way, the solvent canbe continually re-used. The dissolved oil can, however, also be filteredoff again in the system itself during intervals in the process, as willbe described later herein.

[0041] Since the device has been conceived of preferably for mobile use,as a rule electrical energy is available for its operation. However, aheat exchanger heated with natural gas or heating oil is equally usable.The condenser 3 necessary for controlling the process is advantageouslyembodied as air-cooled.

[0042] To protect the vacuum pump or vacuum pump set 10, the condenser 8is cooled by a refrigeration system 9.

[0043] The water vapor liberated in the process and the invading leakingair are aspirated into the condenser 3 via the automatic regulatingdevice 4, in the form of a valve, with the aid of a small quantity ofsolvent vapor. Water vapor and solvent condense in the condenser andcollect in the separation container 5. The solvent flows back into thesolvent loop and once again participates in the heating process in theheat exchanger 16. The water that has precipitated out is pumped out ofthe separation container 5 by the pump 19.

[0044] The further drying process takes place in the same way as in thelarge vapor phase systems in the three references cited above.

[0045] Along with mobile use of the above-described vapor phase system,however, the system can also be used as an economical, stationary devicein conjunction with a vacuum drying boiler.

[0046]FIG. 2 shows a similar embodiment, which however has an expansioncontainer 30, which is disposed near the boiler 1 and whose vaporchamber communicates with the boiler 1 via a short line, which has avalve 31. A line having an expansion valve 18 leads into the expansioncontainer 30. From the sump of the expansion container 30, a line with avalve 32 leads to the feed pump 14. In this embodiment, the evaporationis accordingly performed in the expansion container 30, connectedupstream of the transformer 1 and having an expansion valve 18. Thevapor is delivered to the transformer 1 through the valve 31. Theportion that does not evaporate and that acts as a heat reservoir isreturned externally to the solvent loop through the valve 32. This hasthe advantage that after the heating process, or in intervals betweenheating, for instance during or after an intermediate pressurereduction, the absorbed oil can be filtered off again.

[0047] To that end, the expansion valves 18 on the transformer boiler 1are closed, and the expansion valve 18 on the intermediate container 30and the valves 31 and 32 are all opened. Some of the solvent vaporproduced flows through the valve 31 into the transformer boiler 1, whereit gives up its condensation heat. The other, larger part reaches thecondenser 3 and condenses there. The condensed, pure solvent, such askerosene, flows into the collection container 5 and is emptied as neededinto the container 24.

[0048] In this way, the solvent and oil mixture in circulation isconcentrated, until a residual concentration of solvent in oil thatmeets the temperature and pressure conditions in the transformer 1 andin the condenser (3). The oil, maximally concentrated, is pumped outinto the connected container 24.

[0049]FIG. 3 shows another version, in which an expansion container 30,shown as in FIG. 2, is disposed at a different place, namely above theboiler 1. From its vapor chamber, a line with a valve 31 leads into theboiler 1 and via a valve 34 to the condenser 3. A line with a valve 33also leads from the sump of the condenser 3 into the boiler 1.

[0050] To achieve even better distillation of the solvent portion offfrom the mixture, it is provided as shown in FIG. 3 that theintermediate container 30 is mounted on the transformer boiler 1. As aresult, the transformer 2 can already be supplied during the heatingwith some of the solvent already in vapor form through a valve 31 andwith another portion unevaporated through a valve 33, which serves thepurpose of simultaneous improved rinsing of the transformer interior.

[0051] Once the heating has been concluded, the unevaporated return canbe delivered to the solvent loop through a valve 32, while the vaporproduced in the intermediate container 30 can be delivered to thecondenser 3 through the direct communication with the valve 34. Becauseof the markedly lower pressure, resulting from the direct communicationwith the condenser 3, in the vapor-carrying system (the intermediatecontainer 30 and the condenser 3), a markedly better concentration, withonly small residual quantities of dissolved solvent, is possible.

[0052]FIG. 4 shows a version that is similar to FIG. 3. In FIG. 4, athin-film evaporator 40 is connected to the sump of the expansioncontainer 30, via a valve 41 and a pressure barrier 42. The sump of thethin-film evaporator leads to a valve 32. From the head of the thin-filmevaporator, a line with the valves 47 and 45 leads to a valve 34upstream of the condenser 3, and a tie line between the valves 34 and 35and having a valve 46 leads to the vapor chamber of the expansioncontainer 30 or the vapor valve 31. For heating the thin-film evaporator40, lines with valves 43 and 44 branch off from the hot part of thesolvent loop. The flow rate can be controlled with a valve 48.

[0053] With the version of FIG. 4, a further improvement in thedistillation properties is attained by providing that thealready-concentrated mixture flowing out of the intermediate container30 is delivered not to the valve 33 but rather, via the valve 41 and thepressure barrier 42, to the downstream thin-film evaporator 40, whichcan be put into direct communication with the condenser 3 via theconnecting line through the valves 47, 45 and 34. By recirculation ofthe solvent and oil mixture already contained both in the transformersump 1.1 and in the supply container 24, the solvent is filtered offfrom the mixture, except for the tiniest possible small residualamounts.

[0054] Still further improvement can also be attained if the thin-filmevaporator 40 is heated by the incoming flow heated in the heatexchanger 16, by way of the valves 43 and 44.

[0055] Further improvement is obtained if the thin-film evaporator 40 isheated by a second heater loop having a separate heat transfer fluid, asin FIG. 7.

[0056] Instead of the pressure barrier 42 acting by gravity, a feed pump73 with a valve 74 can also be used. As a result, both the pump 73 andthe thin-film evaporator 40 can be disposed in the mobile part of thesystem, which makes a substantial reduction in the effort and expense ofpreparing for the preparation process possible.

[0057] In many cases, it is impossible, or is possible only with majoreffort, to locate the feed pump 14 far enough below the transformerboiler bottom to assure an adequate geodetic inflow height from thetransformer 1, which is in a vacuum, for proper function of the pump 14.

[0058] The embodiment of FIG. 5 is quite similar to that of FIG. 1, buthere, a feed pump 50 with a control valve 51 and a collection orintermediate container 52 are provided downstream of the outlet valve 12of the boiler sump 1.1. From the sump of the collection container 52, aline leads to the feed pump 14. A bypass line with a valve 53 is alsoprovided, which bypasses the feed pump 14.

[0059] In this respect it is favorable if the solvent flowing out of thetransformer 1 through the valve 12 and optionally carrying oil with itis fed, by a lightweight, easily mounted feeding device, into acollection container 52 located at a higher level of the system. Fromthere, with a type of centrifugal pump that has already proved itselffor the process, it is returned to the expansion valves 18 again via afilter 15 and a heat exchanger 16. Known feed pumps, such as liquid ringvacuum pumps, reciprocating piston pumps, or diaphragm pumps, can beemployed, which are capable of pumping not only liquids and gases butalso vapors as well as mixtures of these components without problems.

[0060]FIG. 6 shows a further version, in which an extremely effectivevariant for recovering the heat transfer medium solvent is provided.This variant again corresponds to that of FIG. 1, except that itadditionally has a thin-film evaporator 60. The headroom of thethin-film evaporator communicates via the valve 64 with the hot part ofthe solvent loop. From its headroom, a line leads directly to thecondenser 3, and from its sump, a line with the blocking valve 63 leadsto the outlet 12 or to the feed pump 14. The valves 61 and 62 regulatethe heating capacity of the thin-film evaporator 60; a second heatexchanger 65 (shown in dashed lines) can be disposed at the heater 17.

[0061] In this version, the solvent and oil mixture, after the end ofheating in the boiler 1 and after the end of the concluding intermediatepressure reduction, can be delivered to the thin-film evaporator 60 fordistillation, instead of to the expansion valves 18. This thin-filmevaporator 60 can be accommodated in the mobile part of the system, sothat no further flexible connections are required between thetransformer 1 and the system, other than the connections already shownin the basic version of FIG. 1 between the components 16 and 18, 12 and14, and between 1 and 7 and 1 and 4.

[0062] The heating is expediently accomplished through a separate heattransfer medium loop having the heat exchanger 65, which can be heatedby the heater 17. The vapor produced in the thin-film evaporator 60 isdelivered directly to the condenser 3. The oil filtered off is deliveredto the container 24. It is advantageous that at little expense forpreparation and installation, excellent results for recovery of thesolvent and for filtering off the transformer oil are attained.

[0063] The variant of FIG. 7 is again similar to that of FIG. 1. Inaddition, however, a thin-film evaporator 70 in the solvent loop isprovided, which can be activated via valves 71 and 72. From its head, ashort line with a valve 31 leads into the boiler 1. It is heated by theheat exchanger 65 via two lines.

[0064] The variants described in conjunction with FIGS. 1-6 functionessentially with expansion vaporization for heating the transformer 1.Only for filtering off the oil or recovering the solvent aredirect-evaporating devices sometimes used. However, the version shown inFIG. 7 is also possible, in which a lightweight, compact thin-filmevaporator 70 is disposed at or on the transformer boiler 1. Theevaporator can be embodied as a commercially available plate evaporatoror similar device. It is supplied with both the solvent and separateheating energy in the form of liquid.

[0065] It is advantageous that here a larger quantity of the deliveredsolvent is evaporated directly, and lesser quantities have to berecirculated. The good heating and filtering results already known fromGerman Patent 196 37 313 C2 are thus attained. List of ReferenceNumerals 1 Vacuum drying boiler or transformer boiler 1.1 Buffer volumeor sump of the transformer 2 Parts, transformer active parts, windings,or insulating parts 3 Condenser 4 Regulating device, valve 5 Separationvessel for heating fluid and water 6 Blocking valve 7 Blocking valve 8Condenser 9 Cooling system 10 Vacuum pump or vacuum pump set 11 Blockingvalve 12 Blocking valve 13 Level sensor 14 Feed pump 15 Filter 16 Heatexchanger 17 Heater 18 Expansion valve 19 Feed pump 20 Blocking valve 21Blocking valve 23 Blocking valve 24 Exchange container 30 Expansioncontainer, additional container 31 Blocking valve 32 Blocking valve 33Blocking valve 34 Blocking valve 40 Thin-film evaporator 41 Blockingvalve 42 Pressure barrier 43 Blocking valve 44 Blocking valve 45Blocking valve 46 Blocking valve 47 Blocking valve 48 Blocking valve 50Feed pump 51 Control valve 52 Collection container 53 Blocking valve 60Thin-film evaporator 61 Blocking valve 62 Blocking valve 63 Blockingvalve 64 Blocking valve 65 Heat exchanger 70 Thin-film evaporator 71Blocking valve 72 Blocking valve 73 Feed pump 74 Valve

1. A device for heating and drying parts (2) with cellulose- or plastic-based hygroscopic electroinsulations, in particular for preparing new or used transformers, condensers, instrument transformers or electric leadthroughs, in a vacuum by means of the condensation heat of the vapor from a heating fluid (solvent, kerosene), wherein during the heating, at least one higher-boiling second fluid, such as transformer oil, occurs from the parts (2), having a vessel, a vacuum pump (10), at least one condenser (3 and/or 8) and a heat exchanger (16) for the heating fluid, characterized in that the heat exchanger (16) heats the heating fluid, leaving it in the liquid phase, and the evaporation is not effected until on or in the vessel, for instance via expansion valves (18), and/or in an expansion container (30) or evaporator (70) located directly on the vessel.
 2. The device of claim 1, characterized in that it is embodied in mobile form, and that the boiler (1) of the transformer to be heated is used as the vessel.
 3. The device of claim 1 or claim 2, characterized in that the connections between the heat exchanger (16) and the expansion valves (18), between an outlet valve (12) and a feed pump, and between the vessel and one or more blocking valves (4, 7) are disconnectable.
 4. The device of one of the foregoing claims, characterized by a removable exchange container (24) for the heating fluid.
 5. The device of one of the foregoing claims, characterized by portable insulating means, such as insulating plates, insulating mats, wall elements, single- or double-walled supporting air tents, or by portable supplementary heaters.
 6. The device of one of the foregoing claims, characterized by an expansion container (30), disposed on the vessel and having a short line (with valve 31) for the evaporated heating fluid, which container has a return line (with valve 32) for the unevaporated heating fluid.
 7. The device of one of claims 1-5, characterized by an expansion container (30), disposed on the vessel, having a short line (with valve 31) to the vessel for the evaporated heating fluid, having one or two return lines (with valves 32, 33) for the unevaporated heating fluid, and having an inlet line (with valve 34) to a condenser (3).
 8. The device of one of claims 6 or 7, characterized in that the expansion container (30) has a permeable double jacket.
 9. The device of one of the foregoing claims, characterized in that the already-concentrated proportion flowing out of the expansion container (30) is delivered through a valve (41) and a pressure barrier (42) by gravity to a downstream thin-film evaporator (40) for filtering off the rest of the solvent, and the vapor occurring when the pressure has been lowered is delivered through the valve (45) directly to the condenser.
 10. The device of one of the foregoing claims, characterized in that the pressure barrier (42) is formed by a feed pump (73) with a valve circuit, and the post-evaporator (40) is set up inside the mobile system.
 11. The device of one of claims 6-10, characterized in that instead of the expansion container (30), a drop-film evaporator and/or a plate evaporator is used, which is preferably heated from the heat exchanger (16).
 12. The device of one of the foregoing claims, characterized by a feed pump (50), designed for low inlet heights, which is preferably embodied as a liquid ring pump or as a positive displacement pump, and by an intermediate container (52) for the heating fluid flowing out of the vessel, with a downstream centrifugal pump for the further pumping of the heating fluid into the heat exchanger (16) and/or into the evaporators (40, 60, 70).
 13. The device of one of the foregoing claims, characterized by a thin-film evaporator (60), with an inlet line to a condenser (3) and with an outlet line to the exchange container (24), in which the thin-film evaporator (60) is heated either by a separate heat transfer medium from a heat exchanger (65) or by the heat exchanger (16) of the heating fluid.
 14. The device of one of the foregoing claims, characterized by a lightweight, compact thin-film evaporator (70), which is secured directly to the vessel and is supplied and heated preferably with heating fluid from the heat exchanger (16) and/or from a further heat exchanger (65). 